The ultimate goal of this research is to understand in molecular detail the interactions involved between the enzyme galactosyl transferase and the "modifier" protein Alpha-lactalbumin. Since general glycosyl transfer by this enzyme occurs in both male and female species in other organs, it is an important example of biological regulation when Alpha-lactalbumin is secreted only in lactating mammary gland to alter the specificity of the system specifically for lactose synthesis. The goals of this current project are to (1) characterize, assign, and map specific cation binding and other regions on the Alpha-lactalbumin moledule in solution, (2) to characterize, describe, and map the substrate (UDPgal) donor site, metal site(s) and (carbohydrate) acceptor site on galactosyl transferase; and (3) to describe the residues and interactions involved in the Alpha-lactalbumin-galactosyl transferase ("lactose synthase") comples, i.e., the role of Alpha-lactalbumin in lactose biosynthesis. These studies will involve ESR, NMR, photo CIDNP NMR, and fluorescene techniques as well as direct chemical and enzymological approaches.